1. Related Applications
This application is related to and may be employed in our co-pending U.S. application Ser. No. 07/066,587 filed June 26, 1987 for "APPARATUS FOR REAL TIME DATA COMPRESSION" by R. L. Frost, K. L. Morley and D. C. Pulsipher, now U.S. Pat. No. 4,926,482.
2. Field of the Invention
The present invention relates to apparatus employed in voice, image and data compression system. More particularly, the present invention relates to a high speed method, and apparatus for analyzing distortion levels in compressed data.
3. Description of the Prior Art
Heretofore it was known that data compression systems existed that would allocate a fixed number of bits to represent a frame of digital data containing a larger number of bits. Further, it was known that transform coding techniques existed which attempted to optimize the signal to noise ratio (SNR) and minimize distortion resulting from data compression systems. A discussion of these techniques is to be found in the following articles:
(1) "Adaptive Transform Coding of Speech Signals (ATCSS)" by R. Zelinski and P. Noll; IEEE Transactions ASSP, Vol. ASSP-25, No. 4, pp. 299-309, August 1977. PA1 (2) "Frequency Domain Coding of Speech", by J. Tribolet and R. Crochiere; IEEE Transactions ASSP, Vol. ASSP-27, No. 5, pp. 512-530, October, 1979. PA1 (3) "Band Width Compression of Voice and Modem Signals Using Variable-Rate ATC Encoding", by D. C. Pulsipher and R. L. Frost; 1986 IEEE Military Communications Conference (MILCOM), Vol. 2 of 3, pp. 32.1.1-32.1.7.
The aforementioned application Ser. No. 07/066,587 is assigned to the assignee of the present invention and shows a real time data compression system. In such transform coding systems it was necessary to make a bit allocation to encode or compress individual frequency coefficients. This referenced system made bit allocations based on an allocation rule designed to maximize the signal to noise ratio, but did not compute or attempt to maintain a predetermined distortion level. Further, it is not known that any data compression system in the prior art employed a distortion analyzer to improve the performance of and/or reduce the cost of data compression systems.
It would be extremely desirable to provide a distortion analyzer capable of providing distortion values of individual frequency coefficients which may be utilized in numerous different ways to improve performance, improve capability and reduce cost of data compression systems.